G-type refers to a classification of stars that are similar to our Sun, categorized under the spectral type G. These stars typically have surface temperatures ranging from about 5,300 to 6,000 degrees Celsius. They emit a yellowish light and are often found in the main sequence phase of stellar evolution, where they spend most of their life. G-type stars are important in the study of astrophysics because they can host planetary systems, including potentially habitable planets like Earth. Their stable energy output allows for the development of life, making them a key focus in the search for extraterrestrial life in the universe.